Manchester United striker Robin van Persie is wary of treating the challenge of Liverpool lightly this weekend as the two rivals clash at Old Trafford on Sunday.

Van Persie, 29, has been in wonderful form since joining United from Arsenal for £24 million in the summer and has plundered 16 goals in 21 league games for his new club.

The Dutchman's form has helped United to the top of the table, where they sit seven points clear of Manchester City and a huge 21 points ahead of the Reds. However, Van Persie is keen not to underestimate the opposition when Brendan Rodgers' men visit Old Trafford.

"It is only seven points, you have to look at it game-by-game" Van Persie told Sky Sports News.

"We still have to go through the entire second half of the league and almost play everyone one more time. Nothing is decided, it will be tough, it will be hard. This weekend we have Liverpool and it's a massive game for us.

"We have to look at the three points and it's a bit like a derby, the teams being so close to each other. There is so much history between them and there have been some great games over the years, going back a long way. They are a great team and, on their day, they can make it a really hard game for us.

"They have a couple of world-class players and we have to look at them, study them, and then do our own bit."